Participation through several government and commercial Launch & Recovery System Projects placed us in the unique position understanding of the various project requirements involving significant technical challenges.

ABS design approved
1000 FSW (300msw) Manned Diving Bell equipped with the dive equipment for up to three divers including helmets and excursion umbilicals.

Saturation diving is a diving technique that allows divers
to avoid the deadly effects of "the bends" so they can work at great
depth for long periods of time.

For diving operations below 50m, a mixture of helium and
oxygen (heliox) is required to eliminate the narcotic
effect of nitrogen under pressure. For extended diving operations at depth,
saturation diving is the preferred approach. A saturation system would be
installed within the Offshore Supply Vessel. A diving bell would transport the
divers between the saturation system and the work site lowered through a 'moon
pool' in the bottom of the ship, usually with a support structure 'cursor' to
support the diving bell through the turbulent waters near the surface. There
are a number of support systems for the saturation system on a Diving Support
Vessel, usually including a diving bell, a transfer chamber, decompression
chamber, launch and recovery systems, winches, reclaim support equipments, control van

Decompression sickness (DCS)

Decompression sickness (DCS) is a potentially fatal
condition caused by bubbles of inert gas, which can occur in divers' bodies
following the pressure reduction as they ascend. To prevent DCS, divers have to
limit their rate of ascent, and pause at regular intervals to allow the
pressure of gases in their body to approach equilibrium. This protocol, known
as decompression stops, can last for many hours for dives in excess of 50 metres (160 ft) when divers spend
more than a few minutes at these depths. The longer divers remain at depth, the
more inert gas is absorbed into their body tissues, and the time required for
decompression increases rapidly. This presents a problem for operations that
require divers to work for extended periods at depth. However, after a few
hours under pressure, divers' bodies become saturated with inert gas, and no
further uptake occurs. From that point onward, no increase in decompression
time is necessary. The idea of saturation diving takes advantage of this by providing
a means for divers to remain at depth for days. At the end of that period,
divers need to carry out a single decompression schedule, which is much more
efficient than making multiple short dives, each of which requires a lengthy
decompression time.

SAT System Elements

A SAT system can be permanently placed on a Vessel of
Opportunity (VOO), but is more commonly capable of being moved from one vessel
to another. The entire system is managed from a control room (van), where
depth, chamber atmosphere and other system parameters are monitored and
controlled. The diving bell is the elevator or lift that transfers divers from
the system to the work site. Typically, it is mated to the system utilizing a
removable clamp and is separated from the system tankage bulkhead by a trunking space, a kind of tunnel, through which the divers
transfer to and from the bell. At the completion of work or a mission, the
saturation diving team is decompressed gradually back to atmospheric pressure
by the slow venting of system pressure, at an average of 15 metres
(49 ft) per day, traveling 24 hours a day (schedules
vary). Thus the process involves only one ascent, thereby mitigating the
time-consuming and comparatively risky process of in-water, staged
decompression normally associated with non-saturation ("mixed gas diving
or sur-D O2") operations.

The divers use surface supplied umbilical diving equipment,
utilizing deep diving breathing gas, such as helium and oxygen mixtures, stored
in large capacity, high pressure cylinders. The gas supplies are plumbed to the
control room, where they are routed to supply the system components. The bell
is fed via a large, multi-part umbilical that supplies breathing gas,
electricity, communications and hot water. The bell also is fitted with
exterior mounted breathing gas cylinders for emergency use.

While in the water the divers use a hot water suit to
protect against the cold. The hot water comes from boilers on the surface and
is pumped down to the diver via the bell's umbilical and then through the
diver's umbilical.